In wireless communications systems such as Long Term Evolution (LTE) and LTE-Advanced (LTE-A) defined by Third Generation Partnership Project (3GPP), wireless LAN defined by The Institute of Electrical and Electronics engineers (IEEE), and Worldwide Interoperability for Microwave Access (WiMAX), a base station (a base station device, downlink transmitting device, uplink receiving device, eNodeB) and a terminal (terminal device, mobile station device, downlink receiving device, uplink transmitting device, UE) include multiple transmit/receive antennas and use multi-input multi-output (MIMO) technology to spatially multiplex data signals and achieve high-speed data communications. In LTE and LTE-A in particular, the orthogonal frequency division multiplexing (OFDM) scheme is employed in the downlink to achieve high spectral efficiency and the single carrier-frequency division multiple access (SC-FDMA) scheme is used in the uplink to reduce peak power. Furthermore, hybrid ARQ (HARQ), which combines automatic repeat request (ARQ) with error correction codes, has been adopted.
FIG. 25 shows a configuration of an LTE communications system implementing HARQ. In FIG. 25, a base station 2501 notifies a terminal 2502 of control information associated with downlink transmit data 2504 over a physical downlink control channel (PDCCH) 2503. The terminal 2502 first performs detection of control information. If control information is detected, the terminal 2502 uses it to extract downlink transmit data 2504. After detecting the control information, the terminal 2502 reports HARQ response information indicating whether the downlink transmit data 2504 has been successfully extracted or not to the base station 2501 over a physical uplink control channel (PUCCH) 2505. Here, a resource for the PUCCH 2505 (PUCCH resource) available for the terminal 2502 is implicitly/tacitly and uniquely determined by the resource for the PDCCH 2503 to which the control information is assigned. The terminal 2502 thus can use a dynamically assigned PUCCH resource when reporting HARQ response information. It is also possible to prevent overlap of PUCCH resources among terminals (see Non Patent Literatures 1 and 2).